1. Field of the Invention
The present invention relates to miniature well pumps and irrigation pumps, and more particularly to an improved miniature irrigation pump apparatus that includes a flexible drive shaft disposed within an elongated well pipe preferably flexible and convoluted that can be placed inside a well casing, wherein the lower end portion of the well pipe carries an axial flow inducer type impeller and the upper end portion of the well pipe communicates with an outlet fitting that enables pumped water to be discharged for irrigation or the like. The outlet fitting includes a mount for a motor/engine drive and wherein a rotary type seal seals the penetration of the flexible drive shaft through the outlet fitting. The pump impeller shaft is supported by wetted bearings to form rotary supports in between the impeller and pump shroud. The pump shroud is loosely supported by the well pipe.
2. General Background of the Invention
Small pumps are often needed for producing a potable water supply for emergency, military or like uses or for use in underdeveloped countries. Such pumps are also needed for irrigation purposes, many times irrigating small fields or to supplement larger irrigation systems. Such pump systems must be cost effective, light weight, and in many cases portable. Power requirements often dictate that only very small engines or motors are available.
A minimum flow requirement for a small pump that would be used to irrigate small acreage lots, for example, would be about one hundred to two hundred (100-200) gallons per minute from a 6-8 inch well (casing diameter) within an approximate water table of about fifteen (15) feet and a draw down to twenty one (21) feet. A yearly average usage as a supplemental pump system would be about 100 hours, for example.
Current small irrigation pumping systems consist of various types. Typical integrated pump and engine systems are compact but are often limited to about twenty (20) feet and the efficiency is about 50% at 12 feet. The xe2x80x9cdown wellxe2x80x9d pumps have much higher efficiencies and will pump from lower levels. These may be shaft driven by an internal combustion engine with a ninety (90) degree gear drive or by an electric motor or a down well sealed electric motor. However, electric motors are disadvantageous because they require power cables to be run out into the field or require an engine driven generator.
Various patents have issued for well pumps and irrigation pumps. One example is the Crespo pump disclosed in U.S. Pat. No. 3,785,752 entitled xe2x80x9cPortable Submersible Pumpxe2x80x9d. The ""752 patent discloses a submersible pump wherein the motor unit is removed from the liquid environment and the motive force for the pump impeller, located in the liquid to be pumped, is transmitted from the motor unit by means of a flexible power shaft. The pump is portable and may have a gear box or a clutch. In addition, the submersible pump may take the form of an axial flow pump when low to moderate lifts are required at large capacities. A spacial flexible shaft terminal is provided wherein the pump and impeller are attached directly to the flexible shaft unit.
A sumpless pump is disclosed in the DeLancey et al. U.S. Pat. No. 3,782,860. The ""860 patent discloses a pump assembly adapted to be installed as a complete assembly in a conventional pipe riser with the pump assembly being so dimensioned that all its parts may be inserted in the upper end opening of a conventional riser of about four (4) inch diameter.
The Gschwender et al. U.S. Pat. No. 4,875,827 discloses a fluid pump that has a casing and a support tube mounted within the casing. A rotatably mounted drive shaft is inserted through the support tube and has a propeller mounted on one end thereof for moving fluid through the pump. A helical shaped bearing is seated between the drive shaft and the support tube for supporting the shaft and permitting fluid flow therethrough.
U.S. Pat. No. 3,799,690, issued to Emil B. Klaas, discloses a pumping apparatus particularly suitable for efficiently pumping relatively large volumes of fluid such as water from one elevation to another including a propeller type blade mounted for rotation adjacent to the immersed open inlet end of a flow conduit of pipe, rotation of said blade establishing a head of water in the conduit, filling the conduit upstream thereof and forcing the fluid to flow through the conduit to be exhausted therefrom usually at a higher elevation. The subject pump is stated to be suited to be operated in tandem with other similar pumping means in the same conduit in situations where it is desired to move the fluid to a considerably higher elevation.
A centrifugal pump with center intake is disclosed in U.S. Pat. No. 2,643,615, issued to R. J. Murphy et al.
The DeLancey et al U.S. Pat. No. 3,7426,473 discloses a pump assembly adapted to be installed as a complete assembly in a conventional or about four (4) inch pump riser as part of a system with the pump assembly being so dimensioned that all of its parts may be inserted in the upper end opening of the conventional riser of about four inch diameter.
An articulate turbine pump is the subject of U.S. Pat. No. 4,082,482.
The Haentjens U.S. Pat. No. 3,163,117 discloses a variable speed cantilevered shaft pump.
The Saltzman U.S. Pat. No. 3,059,849 discloses a water meter accessory that includes an accessory drive flex cable.
The present invention provides an improvement to existing prior art type pumping systems primarily useful in irrigating small fields or supplementing larger systems such as at the corners of large rotary systems.
The pump apparatus of the present invention was designed to pump irrigation water and/or potable water. Therefore, it could be used in an emergency, for military or like use or in underdeveloped countries.
The pumping system of the present invention can be fitted into a small space such as for example a box measuring only a few feet in each dimension or the back of a pick-up truck.
The outlet fitting and flexible well pipe with pump attached could be packaged around an engine, the engine being bolted to a base plate on the outlet fitting. The engine oil (and spares such as air and oil filters) could then be included, the package being installed in less than one hour by placement into an existing well bore.
The present invention thus provides an improved well pump apparatus adapted to be placed in an existing well. The pump apparatus of the present invention includes a well casing that extends under the earth""s surface and includes a bore containing a fluid to be pumped, the well casing having an upper end portion with a flange defining well-head.
A flexible well pipe member extends from the well head down into the well bore to communicate with the fluid to be pumped. The well pipe member includes an upper end portion, a lower end portion, and a flow bore for conveying fluid that is to be pumped between the lower end and the upper end.
An outlet fitting is positioned at the well head, the outlet fitting having a wall portion surrounding a flow bore that enables fluid to be discharged laterally out of the top of the well at the wellhead. An impeller is positioned at the lower end of the flexible well pipe, the impeller being rotatable during pumping for effecting a transmittal of fluid from the lower end portion of the well pipe member to the upper end portion thereof and into the outlet fitting bore for discharge.
In a preferred embodiment, the drive portion includes a motor drive for rotating the flexible drive shaft and a water seal in between the motor drive and flexible drive shaft.
A flexible drive shaft is provided for rotating the impeller, the flexible drive shaft extending in between the impeller and the outlet fitting and including a drive portion, a rotary shaft seal that extends through the wall of the outlet fitting at the well head for communication with a motor drive, engine, or the like. A wetted bearing forms a rotary support in between the impeller and the well pipe, but can be open at both ends to facilitate water lubrication.
The flexible drive shaft is preferably supported at its lower end portion by attachment to the impeller shaft with at least one journal bearing and at least one thrust bearing. The flexible drive shaft is preferably retained and supported by the drive portion of the motor/engine drive.
In a preferred embodiment, the impeller""s rigid drive shaft and the elongated flexible drive shaft are each supported with water lubricated bearings. The impeller is preferably an axial flow inducer type impeller or a mixed axial centrifugal type.
Preferably, a shroud at the lower end portion of the well pipe supports and surrounds the impeller. Preferably, the flexible drive shaft is covered along the majority of its length with a flexible sleeve that protects the well pipe from abrasion. The sleeve is open ended at either of its ends to allow water lubrication and cooling of the drive shaft and rotary shaft seal.
Preferably, a water face seal is provided at the well head that includes a rotating member for sealing water away from the drive portion.
Placement of the flexible drive shaft inside the well pipe provides many advantages which include, but are not limited to increasing ease of handling when placing and removing the unit from a well and during transportation; allowing the flexible shaft to take tensile loads placed on the well pipe; allowing the well pipe to serve as a barrier to the flexible shaft from the external elements; and minimizing overall size of the unit for placement in a well.
While certain novel features of this invention shown and described below are pointed out in the annexed claims, the invention is not intended to be limited to the details specified, since a person of ordinary skill in the relevant art will understand that various omissions, modifications, substitutions and changes in the forms and details of the apparatus of the present invention illustrated and in its operation may be made without departing in any way from the spirit of the present invention. No feature of the invention is critical or essential unless it is so expressly stated as being xe2x80x9ccriticalxe2x80x9d or xe2x80x9cessential.xe2x80x9d